Rust-proof piano-wire



UNITED STATES MARVIN J. UDY AND FRANK C. NICHOLSON, OF KOKOMO, INDIANA, ASSIGNOBQ PATENT OFFICE.

THE UDYLITE PROCESS COMPANY, OF KOKOMO, INDIANA, A. CORPORATION Q] INDIANA.

80 Drawing.

To all whom it may concern:

Be it known that we, MARVIN J. U0: and FRANK C. NICHOLSON, citizens of the United States, residing at Kokomo, in the county of Howard and State of Indiana, have invented certain new and useful Improvements in Rust-Proof Piano-Wire, of which the following is a specification.

The present invention relates to wires for stringed musical instruments and particularly to piano wire, pins and other metallic parts of pianos.

The fact that the process of r usting and of corrosion under the influence of the atmosphere gradually impairs the qualities of piano wire and finally leads to total uselessness has been recognized a long time ago. Continuous efiorts have been made to remedy this evil, but so far as we are advised with little success.

Iron and steel structures are generally protected against the oxidizing action of the atmosphere by covering them with a film of a metal which is not readily attacked. Also non-metallic materials have been used for the same purpose. The first efforts to pro-' tect piano wire were therefore also to coat the wire with a suitable material. It was of course soon realized that out of the number of materials found available for protection of steel and iron in general only comparatively few could find practical ap plication for the specific purpose, since the problem was not merely a coating problem ure and simple. It was soon found that all orms of coating were detrimental to the function of the wire as a sound producer, some more, others less. It was merely a, uestion as to which coating has the least isturbing eflect. Thus we find that gold, silver, copper lead, nickel, tin, brass, cobalt, and a few other metals have almost exclusively been resorted to for the particular purpose. These metals have been applied in various ways and by various processes in unceasing efforts to make the film mechanically as perfect as possible and to reduce the in urious effect upon the tone uality, but so far as we are advised all t ese efforts have been more or less a failure.

Nickel, copper, silver and other non-rusting metals have a distinct tendency to hinder and deaden the vibrations of the wire to Specification of Letters Patent. Patented J unit 28, 1921 Application filed June 13, 1918. Serial 1T0. 304,020.

the extent of materially im airingits tone uality, no matter how even and erfectl t e coating is applied. This defect is prin cipally due to t e fact that a film of these metals 1s inherently relatively thick. and since the modulus of elasticity and other mechamcal characteristics of these metals arematerlally different from those of the steel wlre, the interference with the material function of the wire is considerable. To put some of these metals on a wire requires copperl-platlng first wh1ch renders it practically use ess.

Another drawback found to militate against the successful use of these metals for coating 1s the fact that the coating almost invariably peels off. This is probably due to var1ous causes including rmcipally the diflerence 1n the mechanicai and physical propert1es between them and the steel wire, the lnsufiic ently intimate union between the wire and the coating and perhaps the fact that these metals are themselves not absolutely, lmmune against the action of the atmosphere. While it is not possible to ass1gn w1 th certalnty the causes of the peeling oif, it is probable that under the influence of the vibrations whereby the coating is alternately expanded and compressed the coatmg cracks or breaks and o ens a path for the atmosphere to do its estructive work upon the wire and that the rust thus eats its way laterally of the cracks and destroys the union between the coating and the wire. As small and imperceptible as this initial process of rusting may be at first, it accentuates the crack, 0 ening the way for the atmosphere a litt e further with the result that the portions of the coatin adjacent the crack are free and coil outwar ly as is natural. The continuation of this process is the peeling off of the coating irregularly over the surface with the consequent destruction of the tone quality.

It has also been found that copper-plated wires not only deaden the tone as above pointed out, but also become covered with a green coating which is due to the action of the carbon dioxid in the air which forms copper carbonate and is necessarily injurious tothe function of the wire.

It is ap licants object to provide a rust proof coatlng sufiiciently thin so as not to interfere "sensibly with the normal function of the wire as a sound producer, of such mechanical properties that it does not break under theaction of the vibrations. or on bending or kinking and does not peel ofl'.

The invention will be described herein after in detail and' particularly polnted out a in the claims. I

As has been previously stated, we preferably carry out the invention by covering the wire with afilm of cadmium and the rocess of coating is preferably carried out y electro-platingthe following steps;

I. Prepa/ration of plating sohotz'o'n.

- A solution ,contain in about 25 grams of cadmium per liter 0 solution, we have found, is most convenient for the purpose. Enough of a salt of cadmium such as the sulfate or chlorid to ield 25 grams of metallic cadmium is weig ed and dissolved in as small amount of wateras possible. If metallic cadmium is used, it may be dissolved in hydrochloric acid to form a neutral solution or it may be dissolved in nitric acid and evaporated to dryness wtih hydrochloric acid to remove the nitric acid. After the cadmium is dissolved and is in a neutral or nearly neutral solution, a solution of sodium or potassium hydroxid is slowly added until the cadmium is precipitated and the solution is red to phenolphthalein. Sodium or potassium cyanid'is now slowly added until the precipitated cadmium oxid is all dissolved,-an excess of cyanid being avoided. The solution is then diluted to one liter. The solution as thus prepared constitutes the bath used for electroplating the wire. Other strengths of solution may, of course, be used, but a solution of 25 grams cadmium per liter we find preferable for use. The anode is metallic cadmium. A current density of 7 amperes to 50 am- Iperes per square foot of cathode area can e used. About 7 amperes per square foot are preferred. Lower and higher current densities have been used, and, in fact, the current density does not seem to affect the deposit. Only from 1-5 minutes are requlred and the average time of treating a wire is about 3 minutes. Deposits from this plating solution are very smooth.

II. Gleaning of wire.

Before plating the wire is cleaned of all rust and dirt by polishing with a very fine grade of emery cloth. If necessary, it may also be cleaned by dippin in dilute sulfuric acid or other chemical so utions and finally in water.

111. Eleoh'oplating. After the wire is cleaned it is immediately The treatmentof the wire may comprise electroplated. To do this we preferably coil the wire into a small coil, place it in the cadmium bath and-allowit to uncoil on the bottom of the bath to the sides of the vessel.

One end of the wire is bent so'as to project above the solution to make connection with the circuit. The anode of cadmium is placed in a vertical position in the center of the coil and equally distant from all sides. It extends above the solution to make connection with the circuit'of a D. C. source. This wire when polished issatisfactory/ for the 1 purpose but is improved by the following heat treatment.

IV. Ewin After the wire has received its coating, it is washed in water and laced in an oven and heated to about 150 to 200 C. The maximum in an ordinary oven is about 200 C. Ithas been our p actice to hold the wire at about 185 C. for hours. The time is not a very important factoras good results were obtained by heatin for'24 hours. Any

reasonable length of time, from 2 to 24 hours will serve the purpose well. The temperature should be such that there is only a slight coatin of cadmium oxid formed on the wire. xcessive oxidation must be avoided. By burying the wire in calcium q pens that the coating is too thick. After the heat treatment the coating is very resistant to wear. Since the coating is very thin, th1s resistance is very important.

v. Polishing.

After the wire is thus treated it is bufied and polished. This removes the slight coatin of cadmium oxid and leaves a bright p0 ish on the surface. To give the wire' a finishing touch and a very fine polish, it maybe replaced in the electroplatin bath them r e ectro- Their tensile strength is not impaired.

The coating is exceedingly thin.

The coating is integral with the wire and alloyed thereto.

The tone qualities of the wire are not impaired.

We claim 1. A metal article having a cadmium alloyed thereto.

2. A vibratory element for sound-producing instruments having a thin coating of cadmium.

3. A vibratory element for sound-producing instruments having a thin coating of cadmium alloyed thereto.

4. A piano wire having a thin coating of cadmium.

5. A piano wire having a thin coating of cadmium alloyed thereto.

6. The process of coating metal articles, which consists in first applying a thin coating of cadmium and then subjecting the coated article to heat under conditions causing an alloying of the coating and the metal of the article.

7. The process of coating metal articles, which consists in first electrodepositing a thin coating of cadmium and then subjecting the coated article to heat under conditions causing an alloying of the coat and the metal of the article.

8. The process of treating vibratory elements of sound-producing instruments to make them rust-proof, which consists in first applying a thin coating of cadmium and then sub ectmg the coated element to heat coating of under conditions causing the coating and the metal of the element to alloy.

9. The process of treating vibratory elements of sound-producing instruments to make them rust-proof which consists in first electrodepositing a thin coating of cadmium and then subjecting the coated element to heat under conditions causing the coating and the metal of the element to alloy.

10. The process of treating vibratory elements of sound-producing instruments to make them rust-proof, which consists in first electrodepositing a thin coating of cadmium, then subjecting the coated element to heat under conditions causing the coating to alloy to the metal of the article, and to be outwardly oxidized and then polishing the elements.

11. The process of treating a piano wire to make it rust-proof, which consists in electroplating the wire with a thin coating of cadmium, then heating the Wire to alloy the coating to the wire and then polishing the wire.

12. The process of treating a piano wire to make it rust-proof, which consists in electroplating the wire with a thin coating of cadmium, then subjecting the wire to heat under conditions which cause the coating to alloy to the wire and to be outwardly oxidized and then polishing the wire.

In testimony whereof we afiix our signa- MARVIN J. UD-Y. FRANK C. NICHOLSON. 

